Composite materials bonded with siloxane containing polyimides

ABSTRACT

COMPOSITE MATERIALS ARE PREPARED BY TREATING MATERIALS WITH A SILOXANE CONTAINING POLYAMIC ACID BLOCK COPOLYMERS AND THEREAFTER CONVERTING THE POLYAMIC ACID BLOCK COPOLYPOLYIMIDE STATE. THE POLYAMIC ACID BLOCK COPOLYMERS ARE OBTAINED FROM THE REACTION OF AN ORGANIC DIAMINE, AN ORGANIC TETRACARBOXYLIC DIANHYDRIDE, AND A POLYSILOXANE DIAMINE IN A SUITABLE ORGANIC SOLVENT.

"United States Patent ABSTRACT OF THE DISCLOSURE Composite materials are prepared by treating materials 'With a siloxane containing polyamic acid block copolymers and thereafter converting the polyamic acid to the polyimide state. The polyamic acid block copolymers are obtained from the reaction of an organic diamine, an organic tetracarboxylic dianhydride, and a polysiloxane diamine in a suitable organic solvent.

Recently considerable interest has been shown in polysiloxane amides and polysiloxane amide imides useful for insulation and protective purposes where resistance to heat and corona are important requirements. Holub et al. in U.S. Pat. 3,598,784 discloses the preparation of polysiloxane amides and polysiloxane amide imides from the reaction of an organic diamine, a tetracarboxylic dianhydride and a polysiloxane containing terminal siliconbonded groups, wherein R is a divalent hydrocarbon radical, and Z is a halogen, hydroxyl or methoxy radical.

In our copending application, Ser. No. 185,905 and filed Oct. 1, 1971, we have disclosed that a prepolymer can be formed by the reaction of a siloxane containing diamine, trimellitic anhydride and an organic diamine.

These prepolymers can then be reacted with dianhydrides to form polymers which are useful for preparing films, coatings and adhesives with corona resistance which cure to novel polyamide-imides. The polymers when coated on fibers such as glass, boron, quartz, and carbon fibers or fabric and various finely divided materials such as metals, carbon, quartz alumina and other ceramics represent coated material structures which have good adhesion to the polymeric matrix.

In accordance with the present invention, we have discovered a method of making a composite material by (a) Forming in a solvent a fluid of a block copolymer having recurring structural units of the formula:

wherein R is a divalent hydrocarbon radical, R is a monovalent hydrocarbon radical, R" is a tetravalent or;

and

3,740,305 Patented June 19, 1973 ganic radical, Q is a divalent organic radical which is the residue of an organic diamine, x is an integer having a value of 1-4, m is an integer greater than 1, n is an integer greater than 1, and the recurring units designated by m and u are such that the mol percent of m is equal to 5-'50% of the polymer,

(b) Applying a coating of the fluid to the surface of a first substrate material selected from the group consisting of glass, ceramics, metals, and thermoplastic poly mers,

(c) Attaching to said coated first material a second substrate material selected from the same group as said first material, and l ((1) Converting said block copolymer of Formula I to the corresponding imide to form a bonded composite material. The invention also includes the composite materials bonded with block copolymer of Formula I obtained by the described process.

The block copolymer of Formula I above can be prepared by effecting a reaction of a mixture of ingredients comprising a diamino siloxane of the general formula:

(II) R R NH R S iO SiR-NH- a diamino compound of the formula:

(III) NH -Q-NH and a tetracarboxylic acid dianhydride having the formula:

wherein R, R, R", Q and x have the meanings given above.

The diamino siloxanes of Formula II which may be used in the practice of the present invention are limited in that when x is 5 or more they lose their adhesive properties and, consequently, x may equal 1-4. These include compounds having the following formulas:

etc.

The diamines of Formula 111 above are described in the prior art and are to a large extent commercially available materials. Typical of such diamines from which the prepolymer may be prepared are the following:

m-phenylenediamine; p-phenylenediamine; 4,4-diaminodiphenylpropane; 4,4'-diaminodiphenylmethane; benzidine;

4,4'-diaminodiphenyl sulfide; 4,4-diaminodiphenyl sulfone; 4,4-diaminodiphenyl ether; 1,5-diaminonaphthalene; 3,3'-dimethylbenzidine;

3,3 '-dimethoxybenzidine;

2,4-bis fl-amino-t-butyl toluene; bis(p- 3-amino-t-butylphenyl)ether; bis p-fi-methyl-o-aminopentyl benzene; l,3-diamino-4-isopropylbenzene; 1,2-bis(3-aminopropoxy)ethane; m-xylylenediamine; p-xylylenediamine;

bis (4-aminocyclohexyl)methane; decamethylenediamine; 3-methylheptamethylenediamine; 4,4-dimethylheptamethylenediamine; 2,1 l-dodecanediamine; 2,2-dimethylpropylenediamine; octamethylenediamine; I 3-methoxyhexamethylenediamine; 2,5-dimethylhexamethylenediamine; 2,5 -dimethylheptamethylenediamine 3-methylheptamethylenediamine; S-methylnonamethylenediamine; 1,4-cyclohexanediamine; l,l2- octadecanediamine;' bis(3-aminopropyl) sulfide; N-methyl-bis (B-aminopropyl) amine; hexamethylenediamine; heptamethylenediamine; nonamethylenediamine;

and mixtures thereof. It should be noted that these diamines are given merely for the purpose of illustration and are not considered to be all inclusive. Other diamines not mentioned will readily be apparent to those skilled in the art.

The tetracarboxylic acid dianhydrides of Formula IV may further be defined in that the R" is a tetravalent radical, e.g., a radical derived from or containing an aromatic group containing at least 6 carbon atoms characterized by benzenoid unsaturation, wherein each of the 4 carbonyl groups of the dianhydride are attached to a separates carbon atom in the tetravalent radical, the carbonyl groups being in pairs in which thegroups in each pair are attached to adjacent carbon atoms of the R radical or to ca bon atoms in the R radical at most one Illustrations of dianhydrides suitable for use in the present invention (with their furture designation in parentheses) include:

pyromelliticdianhydride (PMDA); 2,3,6,7-naphthalene tetracarboxylic dianhydride; 3,3',4,4-diphenyl tetracarboxylic dianhydride; l,2,5,6-naphthalene tetracarboxylic dianhydride; 2,'2',3,3'-diphenyl tetracarboxylic dianhydride; 2,2-bis(3,4-dicarboxyphenyl)propanedianhydride;

1 bis(3,4-dicarboxyphenyl) sulfone dianhydride;

benzophenone tetracarboxylic acid dianhydride (BPDA); perylene-l,2,7,8-tetracarboxylic acid dianhydride; bis(3,4-dicarboxyphenyl)ether dianhydride; and

bis 3,4-dicarboxyphenyl methane dianhydride;

- to fibers such as glass, boron, quartz, carbon fibers and fabrics and various finely divided materials such as metals, carbon, quartz, alumina and ceramics. This procedure is particularly useful in treating glass and metallic surfaces to obtain good adhesion to organic thermoplastic polymers such as those described above.

Application of the block copolymer fluid in a suitable solvent or diluent (including, for example, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and water) to the substrate material may be by conventional means such as dipping, spraying, etc. The block copolymer fluid may be dried in an initial heating step at temperatures of about C. for a sufiicient time frequently under vacuum to remove the solvent or diluent. The substrates in the form of sheets, fabric, fiber or particles are then sealed to one another which may and frequently involves the use of pressure. Then the amic acid is converted to the corresponding imid'e by heating at temperatures of about ISO-300 C. for a sufiicient curing time at elevated pressures preferably of about 100 500 p.s.i. to produce the bond. In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation.

EXAMPLE I To a reaction flask flushed with nitrogen were charged a mixture of 24.4 g. N-methylpyrrolidone ,l5.86 g. (0.08 m.) p,p'-methylene dianiline, 5.52 g. (0.02 m.) 1,3- bis- (a-aminobutyl)tetramethyldisiloxane. The mixture was stirred and then 32.22 (0.1 m.) benzophenone tetrac'arboxylic dianhydride was added and stirring was continued until a homogeneous viscous fluid was obtained.

The following reactions were performed by coating one side of a polymer designated as Film A as indicated, with 1 mil of the above viscous solution using a draw bar. The coated film was then heated at a temperature of about 100 C. for 1-4 hours to remove most of the volatile while the coating remains uncured. Thereafter, the coated side of the film was placed in contact with a second polymer designated as Film B. The composite was placed in a press at a temperature for curing of the coating and at a pressure (with or Without vacuum) for a'specified time.

TABLE I Experiment number Film A Heating step Film B Pressing and curing step 1 Plyimide. 2. Polyamide. 3.. Polyamideirnide 4... Polyethylene terephthalate. 5.... Polycarbonate 6 P01 id The resultinng composites of'two films bonded together 10 were obtained with good adhesion between individual by the po'lysiloxane iniide interface showed good adhesion strands. and no evidence of blisters or bubbles in the matrix. EXAMPLE V EXAMPLE II Following the procedure of Example I, 32.2 g. (0.10

Followin the rocedure of Exam k I a mixture of m.) benzophenone dianhydride was added to a solution 211.1 bfmethylipyrrolidonei (0'09 m) of 16 g. i008 In.) p,p-methylene dianiline, 5.5 g. (0.02 methylene dianiline, 2J6 (001 m) 1,3 biS(5 aminO m.) l,3-b1s(6-am1nobutyl?tetramethyldisiloxane and 50 g. .butyl)tetramethyldisiloxane, was Stirred and than 32.22 N-methylpyrrolldone. This mixture was then diluted with g. 0.1 m.) benzophenone tetracarboxylic dianhydride was 200 1% of Water- The aqueous p y Solution Was used added. The mixture was stirred until a homogeneous vis- 20 to coal glass cloth and glass fibers to yield a thin Sizing cous fluid was obtained. coating upon being cured at a temperature of 250-400 Bonded composite materials were formed using the C. The coated glass gave good adhesion to other imides procedure of Example I as shown in the table below: in the formation of laminates.

TABLE II 1:1 mixture of benzophenone tetraearboxylic dianhydride and methylene dlanlline.

The resulting composite materials showed good adhe- EXAMPLE VI sion and no evidence of blisters in the matrix.

EXAMPLE H1 Following the procedure of Examplel, attempts were made to determme the optimum compositions for making FOHOWlng the Procedure of Example a mlXtllTe of composite materials wherein the polysiloxane imide 220-4 2- y py 11-90 PM exhibited good adhesion to the substrate. The mixtures methylene dianiline 11.04 g. (0.04 In.) 1,3-bis-6-aminoare desi y gnated 1n mol percent of benzophenone tetracarbutyl)tetramethyldisiloxane was stlrred and then 32.22 40 g. (0.1 m.) benzophenone tetracarboxylic dianhydride boxyhc dlanhydnde+pp methylene dlamlme (abbrevl was added. The mixture was stirred until a homogeneous ated as BPDA'MDA? m m 3 percent 3 viscous fluid was obtainfid. phenone tetracarboxylic dianhydride-l- 1,3 b1s(6-am1no- Bonded composite materials were formed, using the butyl)tetramethyldisilomne (abbreviated BPDA- procedure of Example I, as shown in the table below: SDA). The compositions and the properties of the cured TABLE III Experiment number Film A Heating step Film B Pressing and curing step 11 Polyimide 100 C./1l1r Polymide 250 G./300 p.s.i./30 min. 12; Polyamideimide- 100 C./2 hrs., 25 Hg. Polyamide-imide.. 200 G./200 p.s.i./30 min.

The resulting composite materials showed good adheproduct using standard procedures are set forth in the sion and no evidence of blisters in the matrix. table below:

TABLE IV Adhesion Composition (moi percent) Cured Cut Bond Bond Experiment film thru Tg to to alunumber BPDA-MDA BPDArSDA integrity 0.) 0.) glass minum 0 100 Flexible... 120 so 50 -.d 220 128 25 o.-- 3.10 195 so 20 ---do-- e50 210 23 it r 1 O-.. ...d 450+ EXAMPLE IV The adhesion test results are indicated as follows:

Following the procedure of Example I and using the no qdheslon I +passmg adhesion viscous fluid prepared from (0.08 m.) p,p -methylene (11- v r 00d db aniline, 0.02 m.) 1,3 bis(6-aminobutyl)tetramethyldi- 70 6 Y g a n siloxane and (0.1 m.) benzophenone tetracarboxylic acid T e data indl es t t he presence of a board range anhydride, strands of glass fibers were dip-coated into the of 1050 mol percent of BPDA-SDA in the coating comviscous fluid. The coated fibers were then'cured by heatposition produces passing adhesion; while when the range ing at a schedule of 100 C./ 15 min., C./l5 min., of BPDA SDA in 10-25 mol percent very good adhe- 200 C./ 15 min., and 300 (31/ 15 min. Fused filaments 75 sion is produced.

It will be appreciated that the invention is not limited to the specific details shown in the examples and illustrations and that various modifications may be made within the ordinary skill in the art without departing from the spirit and scope of the invention.

We claim:

1. A composite material comprising (a) a first substrate material selected from the group consisting of glass, quartz, ceramics, metals, carbon, and thermoplastic polymers;

(b) a second substrate material selected from the same group as said first substrate material; and

(c) an intermediate bonding agent comprising a polyimide having recurring structural units of the formula:

and

wherein R is a divalent hydrocarbon radical, R is a monovalent hyrocarbon radical, R" is a tetravalent organic radical which is the residue of a tetracarboxylic acid anhydride, Q is a divalent radical which is the residue of an organic diamine, x is an integer having a value of 1-4, m is an integer greater than 1, n is an integer greater than 1, and the integers designated as m and n are such that the mol percent of m is equal to 50% of the polymer.

2. The composite material of claim 1, wherein R is lower alkyl, R is lower alkyl, R" is a radical derived from or containing a group of at least 2 carbon atoms, wherein each of the 4 carbonyl groups of the dianhydride are attached to adjacent carbon atoms in the tetravalent radical, and Q is a member selected from the group consisting of alkylene containing from 2-20 carbon atoms, cycloalkylene, alkylcycloalkylene, xylyle'ne, phenylene, lower alkyl phenylene,

wherein X is a member selected from the group consisting of bivalent aliphatic, cycloaliphatic or araliphatic (having 1-8 carbon atoms) 3. The composite material of claim 2, wherein said first substrate and said second substrate are thermoplastic materials selected from the group consisting of polyimides, polyesters, polycarbonates and polyamides.

4. The composite materials of claim 2, wherein said materials are fibers or fabric selected from the group consisting of glass, boron, quartz and carbon fibers.

5. The composite material of claim 4, wherein said materials are fibers or fabric of glass.

6. The composite material of claim 2, wherein said diamino siloxane is 1,3-bis(aminoalkyl)tetramethyldisiloxane, said organic d'iamine is p,p'-methylene dianiline, and said tetracarboxylic acid dianhydride is benzophenone dianhydride.

7. A method of making a composite material comprising the steps of (a) forming in a solvent a fluid of a block copolymer having recurring structural units of the formula:

wherein R is a divalent hydrocarbon radical, R' is a monovalent hydrocarbon radical, R" is a tetravalent organic radical which is the residue of a tetracarboxylic acid dianhydride, Q is a divalent radical which is the residue of an organic diamine, x is an integer having a value of 1-4, m is an integer greater than 1, n is an integer greater than 1, and the integers designated by m and n are such that the mol percent of m is equal to 5-50% of the polymer;

(b) applying a coating of the fluid to the surface of a first substrate material selected from the group consisting of glass, quartz, ceramics, metals, carbon and thermoplastic polymers;

(0) attaching to said coated first material a second substrate material selected from the same group as said first material, and

(d) converting said block copolymer of the formula set forth above to the corresponding imide to form a bonded composite material.

8. The method of claim 7, wherein R is lower alkyl, R is lower alkyl, R" is a radical derived from or containing a group of at least 2 carbon atoms, wherein each of the 4 carbonyl groups of the dianhydride are attached to adjacent carbon atoms in the tetravalent radical, and Q is a member selected from the group consisting of alkylene containing from 2-20 carbon atoms, cycloalkylene, alkylcycloalkylene, xylylene, phenylene, lower alkylphenylene,

wherein X is a member selected from the group consisting of bivalent aliphatic, cycloaliphatic or araliphatic (having 1-8 carbon atoms),

t o -O, --C, S and an organic diamine compound of the formula: Y

9 (3) a tetracarboxylic acid dianhydride having the formula:

0 0 15 ll 0 \R 0 wherein R, R, R", Q and x are defined as hereinabove.

10. The method of claim 9, wherein said diamino siloxane is 1,3-bis(aminoalkyl)tetramethyldisiloxane, said organic diamine is p,p'-methylene dianiline, and said tetracarboxylic acid dianhydride is benzophenone dianhydride.

11. The method of claim 8, wherein said first substrate is a thermoplastic polymer and said second substrate is a thermoplastic polymer.

12. The method of claim 11, wherein said first substrate and said second substrate are selected from the group consisting of polyimides, polyesters, polycarbonates, and polyamides.

13. The method of claim 8, wherein said composites are formed from inorganic substrate materials of fibers References Cited UNITED STATES PATENTS 3,288,754 11/1966 Green -.--4 161-206 X 3,392,144 7/1968 Holub 26046.5 E 3,553,282 l/1971 Holub 260824 R 3,598,783 8/1971 Holub et al. 260-46.5 E 3,598,784 8/1971 Holub et a1. 26046.5 E 3,598,785 8/1971 Holub et a1. 26046.5 E 3,637,550 1/ 1972 Spraner 161-207 CHARLES E. VAN HORN, Primary Examiner US. Cl. X.R.

i161193, 213, 227, 206, 207, 176; 156-329; 260-46.5 E, 824 R 

